In U.S. Pat. No. 3,839,892 there is disclosed a method of ensuring that the dimensions of a rolled ring are accurate by determining the variations in the dimensions of a workpiece from a nominally sized workpiece and then rolling the rings to a depth dependent on the magnitude of the variations or rolling the rings to a constant depth and maintaining the rolls at that depth for a time (dwell time) dependent on the magnitude of the variations.
There is also disclosed a roll forming machine for carrying out that method in U.S. Pat. No. 3,803,890 and 3,839,892.
The difference between the required depth of rolling or dwell time for a given workpiece and that for a nominal sized workpiece is determined by an algebraic relationship formulated from the difference between the wall thickness, width and mean diameter of a nominal sized workpiece and the workpiece under consideration. This method is in fact a way of ensuring diametral control by measuring dimensional variations of a workpiece from the nominal.
This invention differs from that disclosed in U.S. Pat. No. 3,839,892 in that the dimensional variations of the workpiece from the nominal are calculated by measuring the weight variations instead of dimensional variations.